I have a few questions related to statics and rotational dynamics. I have the general idea of what I need to do (at least, I hope I do), but I am having trouble making anything of it. Any input on any of the questions would be greatly appreciated .(adsbygoogle = window.adsbygoogle || []).push({});

The first thing I did was to look at the hanging mass and determine the forces acting on it. I said that the net force is T-1600N=0. Now for the system to remain in equilibrium, I made some assumptions: First, I though of S as a vector. For that vector to remain still, the torque produced by the tension in the direction of the point where the cable is attached to the ground and the torque produced by the tension in the direction of the hanging mass (downwards) must be zero. However, using the first equation I wrote above, I come up with the tension being equal to 1600N. Am I on the right track here? The system shown in the image is at equilibrium. The mass at the end of the uniform strut S weighs 1.60e+3 N; the strut itself weighs 520 N. The image of the system is located at http://show.imagehosting.us/show/971138/0/nouser_971/T0_-1_971138.jpeg

(a) What is the tension in the cable?

(b) What is the horizontal component of the force exerted on the strut by the pivot P?

(c) What is the vertical component of the force exerted on the strut by the pivot P?

I know that the answer to part (c) is RIGHT because it is rolling right producing a contact force to the left, thus a frictional force to the right. This is how I attempted to calculate part (a): A yo-yo, pulled across a table by a force F = 5.00e-2 N as shown, rolls without slipping. It consists of two outside cylindrical pieces, each of radius 2.60 cm and mass 80.0 g, joined together by a central shaft of radius 1.00 cm and negligible mass. The coefficient of static friction between the yo-yo and the table is 0.660; the coefficient of kinetic friction is 0.300. The image of the yo-yo is located at http://show.imagehosting.us/show/971155/0/nouser_971/T0_-1_971155.jpeg

(a) What is the magnitude of the frictional force acts on the yo-yo?

(b) Calculate the translational acceleration of the center-of-mass.

(c) Is the frictional force directed to the left or the right?

[tex]\tau=rF=\left(.05\text{N}\right)\left(.01\text{m}\right)=.0005\,\text{Nm}[/tex]

...now dividing by the larger radius I can find the contact force, which should be equal to the frictional force in magnitude (is this right?):

[tex]\frac{.0005\,\text{Nm}}{.026\,\text{m}}=.019\,\text{N}[/tex]

Thank you very much for the help.

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# A Few Statics-Related Questions

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